Method of stud driving power control



1955 v. R. ERICKSON ETAL 2,722,003

METHOD OF STUD DRIVING POWER CONTROL 2 Sheets-Sheet l INVEN TOR.

E, inc/fawn Filed Dec. 29, 1949 H mlHlnmln WwE/YH United States Patent METHOD or STUD DRIVING POWER coNTRoL Virginius R. Erickson and Benjamin B. Bullwinkle, Portland, Oreg., assignors to Powder Power Tool Corporation, Portland, 0reg., a corporation of Oregon Application December 29, 1949, Serial No. 135,744

1 Claim. (Cl. 1--60) The present invention relates to stud driving tools of the type employed for the explosive installation of studs in various types of concrete and steel structures or bodies, and is concerned particularly with methods of employing a standard explosive charge by varying the effective force of such charge as applied to the stud to obtain a desired selected force for successful installation of a particular stud in a particular wall surface or body. This invention is concerned with power control method and apparatus of the general character disclosed and claimed in the copending application of Roy M. Magnuson, Serial No. 135,114, filed December 27, 1949, for Stud Driving Tool and Method of Power Control, now abandoned.

The present invention provides for varying of the combustion space or chamber in which the explosive charge is exploded and for also varying the spacing of the stud from the muzzle end of the barrel to influence further the energy imparted to the stud by controlling the time during which the stud is subjected to the driving force before emerging from the muzzle end of the barrel.

The above and other objects of the invention are attained in connection with certain preferred procedures for practicing the invention as disclosed and described in connection with the accompanying drawings, in which:

Figure 1 is an elevational view of a stud driving tool with certain parts broken away and shown in section to illustrate the combustion chamber of the tool.

Figure 2 is an enlarged fragmentary view showing the breech plug unit for obtaining maximum driving force onastud.

Figures 3 and 4 are views of other sizes of breech plugs for obtaining different effective stud driving forces.

Figure 5 is a view of a stud setting rod for use where a standard breech plug is employed and the position of the stud is varied along the barrel as desired by the operator.

Figure 6 is a graph illustrating the change on effective force as applied to the stud as accomplished by changing the position of the stud with respect to the muzzle end of the barrel, i. e., by changing the effective length of the barrel through which the stud must be propelled before it engages and penetrates a wall surface.

Figure 7 is a graph illustrating the efiect of change in combustion chamber volume upon the efiective force applied in driving a stud.

Referring to Figure 1, there is shown a stud driving tool of the character described and claimed in the copending applications of Smith and Daugherty, Serial No. 124,078, filed October 28, 1949, for Stud Driving Tool, and Erickson and Bullwinkle, Serial No. 130,818, filed December 2, 1949, and issued as U. S. Letters Patent No. 2,679,645 on June 1, 1954, for Stud Driving Tool. In general, stud driving tools of this character are adapted to be separated or broken into two halves including a rear part 10 which contains the various firing control parts including, for example, a firing pin carrier 11, and a front or barrel part 12 of the tool in which the barrel 13 is included. The barrel 13 is provided with an unob- 2,722,003 Patented Nov. 1 1955 structed stud receiving bore part and an enlarged rear end 13a which has a threaded connection within the end of the firing pin carrier 11 to connect the two halves of the tool. The barrel 13 is also provided with an enlarged bore in which a combustion chamber or breech plug insert 14 is provided for positioning the stud 16 to be driven and in which the explosive cartridge 18 is mounted for impact by the firing pin of the firing mechanism. The tool is broken in two halves by unthreading the front part 12 at the threaded connection of the barrel 13 with the firing pin carrier 11 and sliding this part from within the housing of the rear part 10. With the parts disassembled, the breech plug or insert 14 is removed and the selected stud 16 is installed in the barrel by manually applying force to the head end of the stud to push it longitudinally in the stud receiving bore','ahd discontinuing the pushing before the stud has been given the maximum possible movement and when it has been located at a distance from the breech end of the bore corresponding to the resistanceto stud penetration of the body into which the stud is to be installed. Thereafter the cartridge 18 is'placed in the breech plug 14, and the parts are reassembled as shown in Figure 1 fora firing operation. Firing is accomplished by placing the end of the barrel 13 against the surface into which the stud is to be driven and pressing or telescoping the barrel assembly 12 and the firing pin carrier 11 back into the other part of the tool until a firing position is reached, as disclosed in said applications, and then effecting relative turning movement of the central housing and the end grip to fire the tool. At this time the deflector pad structure 19, yieldably mounted about the barrel 13, is engaged with the surface about the area of engagement of the end of the barrel so as to provide protection front flying particles of the Wall surface upon explosive installa: tion of the stud.

As previously stated in accordance with the instant:

invention, the effective force of the standard explosive in spaced relation with respect to the breech andmuzzle ends of the barrel and the cartridge. As a result, at the same time that the volume of the combustion chamber is' varied, the effective length of the barrel through which the stud is driven by the explosive charge is also changed,

and these two factors are combined in varying the power control in driving the stud. i

As seen in Figure 1 the breech plug 14 is provided with a cylindrical extension 21 which extends within and fits closely within the bore of the barrel 13 so that by placing the stud in the barrel and then inserting the breech plug 14, the stud is positioned at a predetermined spacing both with respect to the cartridge 18 and with respect to the muzzle end of the barrel 13. Preferably the stud 16 is constructed to frictionally maintain its position within the barrel, and in the present instance, the stud 16 is knurled or dimpled at 16a around its head so that its position in the barrel will be maintained and yet the stud can be driven from the barrel by explosive force of the cartridge 18.

Figure 2 shows the highest power or breech plug 17b which has no cylindrical extension so that the stud is positioned immediately adjacent the end of the cartridge 18. Figures 3 and 4 illustrate other breech plugs of the set to select the position of the stud in the barrel.

Figure 5 shows a power selector stud positioning rod 22 having graduations 22a along its length to indicate the extent of positioning of the stud within the barrel. The grooved graduations 22b correspond to the stud positions obtained with the various length breech plugs. The rod 22 carries a stop collar 23 for cooperation with the graduations, the collar 23 being held in place on the rod by a set screw 24. In employing the power positioning rod 22, the breech plug of 17b of Figure 2 is used and the rod is employed to push the stud 16 to the desired position along the barrel for the particular effective power which is to be employed in driving the stud.

The reduced end 22c of the rod positioning rod 22 may be employed for removing a cartridge 18 from the breech plug when it becomes stuck because of expansion during the explosion process.

Referring to Figure 7 there is shown a graph illustrating the relation of change in combustion volume to effective force applied to the stud, i. e., to effective penetration of the stud into a given surface, in which the vertical coordinate is the amount of stud penetration in mild steel, reading in 64th of an inch, and the horizontal coordinate is combustion chamber volume in cubic inches. The curve is plotted from experimental data and approximates closely actual change in effective force in driving the stud for change in volume of the combustion chamber. It will be noted, for example, that in changing the volume from cubic inch to 7 cubic inch, i. e., in doubling the volume, the effective penetration of the stud into the steel surface decreased from to a difi'erence in penetration of Ms Figure 6 illustrates the change in penetration or effective force applied to the stud in accordance with the change in barrel length which is a factor to control the size of the combustion chamber. The vertical coordinate again is penetration on a scale of 1 per divisions while the horizontal coordinate denotes barrel length in inches (distance from the head of the stud to the muzzle end of the barrel). In connection with this curve, it will be noted that from about 10 barrel length to 20 barrel length the effective force varies slightly. By decreasing the efiective barrel length below 10'' there is a sharp change in the effective penetrating force as the time in which the gases can apply their force in propelling the stud is materially decreased. In practice, the full power or effective force is applied with the barrel length of from 10" to 12" in length while the successive spacing of the stud 16 along the barrel at successively smaller distances from the muzzle end of the barrel produces a decrease in the effective force as shown by the curve of the graph.

It will be appreciated that this invention combines the two factors of change in combustion chamber volume and change in effective barrel length to obtain the desired range of eifective driving forces in setting studs into surfaces.

It is apparent from the above description that the invention contemplates the use of a selected explosive charge which is a standard one, i. e., of a given selected size or power so that the same constant explosive force is present in each firing, but only as much explosive force is utilized as required by the particular wall surface or body in which the stud is to be installed. It will be appreciated that various sizes of standard cartridges may be employed.

While we have shown and described certain preferred methods and apparatus for carrying out the invention it Will be understood that the invention is capable of variation and modification from the form shown so that its scope should be limited only by the scope of the claim appended hereto.

We claim:

In a method of installing a stud in a body by subjecting the stud to an explosive driving force in a stud driving tool provided with a bore having a breech end, a muzzle end and an intervening unobstructed stud receiving bore part at any of a number of positions along which a stud may be located, the steps of inserting a stud through said breech end into said stud receiving bore part; manually applying force to the stud to move it longitudinally in said stud receiving bore part; discontinuing the application of stud moving force to the stud before it has been given the maximum possible movement in said stud receiving bore part and when said stud has been located at a distance from said breech end with relation to the desired stud penetration with relation to the resistance of the body, the discontinuance of manual application of force to the stud alone determining the location of the stud with reference to the breech end; after the locating of the stud separately inserting into said breech end a cartridge of explosive charge of constant magnitude irrespective of the resistance of said body to stud penetration; and firing said cartridge, the longitudinal location of said stud in said bore part relative to said cartridge being a factor to control the size of a combustion chamber to control the stud driving effect of the explosive charge according to the desired stud penetrating force.

References Cited in the file of this patent UNITED STATES PATENTS 1,277,370 Bovard Sept. 3,1918 1,388,363 Miller Aug. 23,1921 2,064,503 Temple Dec. 15, 1936 2,158,763 Sabol May 16,1939 2,359,515 Fanger Oct. 3,1944 2,395,354 Temple Feb. 19, 1946 2,499,227 Miles Feb. 28,1950 2,533,851 Temple Dec. 12, 1950 2,549,993 Temple Apr. 24, 1951 

